Climate Change and Sea Level Rise a Review of the Scientific Evidence

48525 Paper number 118 ENVIRONMENT DEPARTMENT PAPERS Climate Change Series Environment Department THE WORLD BANK 1818 H Street, NW Washington, D.C. 20433 Telephone: 202-473-3641 Facsimile: 202-477-0565 Climate Change and Sea Level Rise A Review of the Scientific Evidence Susmita Dasgupta and Craig Meisner May 2009 Sustainable Development Vice Presidency Printed on recycled paper stock, using soy inks. THE WORLD BANK ENVIRONMENT DEPARTMENT Climate Change and Sea Level Rise A Review of the Scientific Evidence Susmita Dasgupta Craig Meisner May 2009 Financial support for this study was provided by the Research Department of the World Bank and the Canadian Trust Fund (TF030569) sponsored by the Canadian International Development Agency (CIDA). We would like to extend our special thanks to Kiran Pandey for his valuable help. We are also grateful to David wheeler, Michael Toman and Rawleston Moore for useful comments and suggestions. Papers in this series are not formal publications of the World Bank. They are circulated to encourage thought and discussion. The use and citation of this paper should take this into account. The views expressed are those of the authors and should not be attributed to the World Bank. Copies are available from the Environment Department of the World Bank by calling 202-473-3641. © The International Bank for Reconstruction and Development/THE WORLD BANK 1818 H Street, N.W. Washington, D.C. 20433, U.S.A. Manufactured in the United States of America May 2009 The findings, interpretation, and conclusions presented in this report are those of the author and should not be attributed to the World Bank, its affiliated organizations, or to members of its Board of Executive Directors or the countries they represent. The presentation of material in this document and the geographical designations employed do not imply expression of any opinion on the part of the World Bank concerning the legal status of a country, territory or area, or concerning the delimitation of its boundaries. Design: Jim Cantrell Cover photos: Perito Moreno Glacier, Argentina; © Shutterstock Images, LLC Contents Abstract v Section 1: Introduction 1 Section 2: Climate Change and SLR — Observations from the Past 3 Ocean thermal expansion 3 Changes in glaciers and icecaps 3 Glacial melt from Greenland and Antarctica 3 Snow on land 4 Permafrost 4 Section 3: Sea Level Rise — Predictions 6 Ocean thermal expansion 6 Glaciers and icecaps, Greenland Ice sheet, Antarctic Ice sheet, snow on land, and permafrost 6 Projections of mass balance sensitivity of glaciers and ice caps 7 Greenland and Antarctica Ice Sheets 8 Likelihood of abrupt changes 8 Projections of global SLR by IPCC AR4 9 Section 4: Recent Evidence for the Greenland and Antaractic Ice Sheets 10 Greenland Ice Sheet 10 Antarctic Ice Sheet 11 Section 5: Other Projections of SLR 13 Section 6: Conclusion 15 Impacts of SLR on storm surge height 15 References 17 Appendix 1 — Source of Data on Major Contributory Factors to SLR 22 Ocean thermal expansion 22 Greenland Ice Sheet, Antarctic Ice Sheet 22 Glaciers and ice caps (not immediately adjacent to Greenland and Antarctic ice sheets) 23 Climate Change Series iii Climate Change and Sea Level Rise — A Review of the Scientific Evidence Snow on Land 23 Permafrost 24 Appendix 2 — The Emission Scenarios of the IPCC Special Report 25 Endnotes 26 Tables Table 1. Contributions to SLR Based Upon Observations as Compared to Models Used in the IPCC AR4 4 Table 2. Area, Volume and Sea Level Equivalent (SLE) of the Other Major Contributory Factors to SLR 7 Table 3. Mass Balance (MB) of the East Antarctic (EAIS), West Antarctic (WAIS), Antarctic (AIS), and Greenland (GIS) Ice Sheets as Determined by a Range of Techniques and Studies 10 iv Environment Department Papers Abstract ea-level rise (SLR) due to climate change is a There appears to be a consensus across studies that serious global threat: The scientific evidence is now global sea level is projected to rise during the 21st overwhelming. The rate of global sea level rise was century at a greater rate than during the period 1961 faster from 1993 to 2003, about 3.1 mm per year, to 2003 and unanimous agreement that SLR will not Sas compared to the average rate of 1.8 mm per year be geographically uniform. Ocean thermal expansion from 1961 to 2003 (IPCC, 2007); and significantly is projected to contribute significantly, and land ice will higher than the average rate of 0.1 to 0.2 mm/yr increasingly lose mass at an accelerated rate. But most increase recorded by geological data over the last 3,000 controversial are the mass balance loss estimates of the years. Anthropogenic warming and SLR will continue Greenland and Antarctic Ice Sheets and what the yet for centuries due to the time scales associated with un-quantified dynamic processes will imply in terms of climate processes and feedbacks, even if greenhouse gas SLR. Recent evidence on the vulnerability of Greenland concentrations were to be stabilized. This paper reviews and west Antarctic ice sheets to climate warming raises the scientific literature to date on climate change and the alarming possibility of SLR by one meter or more sea level rise. by the end of the 21st century. Climate Change Series v 1 Introduction ea-level rise (SLR) due to climate change is a in coastal regions. The biophysical effects of SLR on serious global threat: The scientific evidence is now coastal regions include: i) inundation, flood and storm overwhelming. The rate of global sea level rise was damage; ii) wetland loss; iii) erosion; iv) saltwater faster from 1993 to 2003, about 3.1 [2.4 to 3.8] intrusion v) coral bleaching (from higher sea water Smm per year, as compared to the average rate of 1.8 temperatures); vi) ocean productivity changes; and [1.3 to 2.3] mm per year from 1961 to 2003 (IPCC, vii) species migration. Most of these impacts are 2007); and significantly higher than the average rate of broadly linear functions of sea level rise, although 0.1 to 0.2 mm/yr increase recorded by geological data some processes such as wetland loss and change show a over the last 3,000 years.1 threshold response and are more strongly related to the rate of sea level rise, rather than the absolute change. Even if greenhouse gas (GHG) emissions were These natural-system effects have a range of potential stabilized in the near future, sea levels would continue socio-economic impacts, including the following to rise for many decades (IPCC, 2007). Until recently, identified by McLean and Tsyban (2001): i) increased studies of SLR typically predicted ranges within the loss of property and coastal habitats, ii) increased flood 0-1 meter during the 21st century (Church et al., risk and potential loss of life, iii) damage to coastal 2001). The IPCC AR4 report has projected a rise in sea protection works and other infrastructure, iv) loss of level between 0.18 to 0.59 meters by the end of 21st renewable and subsistence resources, and v) loss of century - across different emission scenarios. However, tourism, recreation, and transportation functions. the models considered by the IPCC, 2007 did not include the full effect of changes in ice sheet flow, The impacts of SLR could be catastrophic for many and IPCC projections have been criticized by many developing countries. Recent World Bank estimates experts as being too conservative (Oppenheimer et al., suggest that even a one-meter rise in sea level in coastal 2008; Pfeffer et al., 2008; Solomon et al., 2008). New countries of the developing world would submerge measurement information on the rates of deglaciation 194,000 square kilometers of land area, and displace in Greenland and the West Antarctic suggest an at least 56 million people (Dasgupta et al. 2007). The alarming possibility that a threshold triggering many actual impacts, however, will depend on countries’ meters of sea level rise could be crossed well before ability to adapt to the potential impacts of SLR. the end of this century (Hansen et al., 2007; Helsen et al., 2008; Joughin et al., 2008; Kohler et al., 2007; The impacts of climate change on sea level rise are Overpeck et al., 2006; Rignot, 2008; Van de Wall et al., complex. At play are the interactions between natural 2008).2 cycles and human activity, and a full assessment of the range of climate change consequences and probabilities SLR is a serious threat to countries with high involves a cascade of uncertainties in emissions, carbon concentrations of population and economic activity cycle response, climate response, and impacts. In this Climate Change Series 1 Climate Change and Sea Level Rise — A Review of the Scientific Evidence paper we review the scientific literature on climate future. Section 4 then provides an overview of the change and SLR to date. latest research on SLR and serves as an update to the IPCC AR4 report. Section 5 provides an overview of In the next section we begin with a summary of the some of the criticisms of the IPCC AR4 report and historical observations as noted by the IPCC in their section 6 concludes the review. latest report and in section 3, their predictions for the 2 Environment Department Papers Climate Change and SLR — 2 Observations from the Past (as summarized in the IPCC AR4 report) he IPCC AR4 Report identifies several major 2003 had much higher rates of warming, especially in factors that currently contribute to sea level the upper 700 m of the global ocean. change. These are: T Changes in glaciers and icecaps • Ocean thermal expansion3 During the 20th century, glaciers and ice caps have • Changes in glaciers and icecaps experienced widespread mass losses.

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